One known type of information storage device is a disk drive device that uses magnetic media to store data and a movable read/write head that is positioned over the magnetic media to selectively read from or write to the magnetic media. Recently, there has been an increasing demand for portable data storage devices.
Shock and collision are the two most harmful factors affecting the functionality of the disk drive when being in use. When the computer comes across the shock or collision, the reading and writing processes of the disk drive may easily be affected by unbalanced resonance frequency between the operation of the disk drive and the computer by external shocks. Therefore, an anti-shock effect is provided by an anti-shock design of the disk drive, for instance, there is a buffer designed between the disk drive and the disk drive rack. This arrangement preliminary prevents the disk drive from shock physically. Along with the development of the computer industry, all elements used in the computer have been made toward miniaturization, preciseness, high functionality and high stability. As the design of computer architecture, this additional buffer component is not desired to arranged in such compact hard disk drive, furthermore, the anti-shock function of the buffer component is merely could prevent bigger shock, and it could not stop the slider writing on/reading from the disk, so it would bring damage to the disk.
FIG. 1 provides an illustration of a typical disk drive 100. Referring to FIG. 1, a typical disk drive 100 includes a head stack assembly (HSA) 110 with one or several head gimbal assemblies (HGA) 111 having sliders thereon, a magnetic disk 120 mounted on a spindle motor 130 which causes the magnetic disk 120 to spin, and a motor base 140 to enclose the above-mentioned components. The sliders flies over the surface of the magnetic disk 120 at a high velocity to read data from or write data to concentric data tracks on the magnetic disk 120, which is positioned radially by an arm coil assembly (ACA) 112 having (e.g. by epoxy potting or overmolding) a fantail spacer 113. Generally, a voice coil motor (VCM) 114 embedded in the fantail spacer 113 is used to drive the ACA 112. The HSA 110 further includes a printed circuit board assembly (PCBA) (not shown) with a flexible printed cable (FPC) 116. The PCBA and the ACA 112 are connected together by the flexible printed cable (FPC) 116 to form an arm flexible circuit assembly (AFA).
In prior art, referring to FIGS. 1-2, a head disk interface sensor (HDI sensor) 121 is deposited in the slider to work as Touch Down detection (TD detection). The HDI sensor 121 is normally applied on a constant working current via the PCBA. When the HDI sensor 121 gets close to the rotary disk 120, the resistance of the HDI sensor 121 is changed based on the cooling effect from the rotary disk 120, then the voltage of the HDI sensor 121 is changed correspondingly. TD detection is carried out by the slider flying to touch the disk 120, and then a zero point is obtained. Based this zero point, the slider is applied on a predetermined voltage for flying on the disk 120, and based on the output changing voltage of the HDI sensor 121, the fly height is accurately under control. This HDI sensor 121 is characteristic of high sensitivity. Referring to FIGS. 1-2, a shock sensor is provided in the Drive Printed Circuit Board (Drive PCB) which is located under and connected the PCBA, for sensing the vibration of the disk drive 100 caused by the shock or the collision. When the shock sensor sense the shock or the collision, it would input changing voltage into the controller, if the voltage trigger the threshold set in the controller, the controller would close the operation current to the HSA, and control the HSA 110 to load on the ramp 117, for anti-shock protection, and the disk drive 100 stops operation. As the high accurate requirement of slider operation, the disk which the slider directly contacts to is the mainly to be protect, and the slider is the target object to be monitored. However, the traditional shock sensor is mounted in the drive PCB, and it is far from the slider, so the sensitivity of the shock sensor for sensing the shock or collision of the slider is low. This low sensitivity probably results in big damage of the disk drive, and it does not meet the high accurate requirement of slider operation.
Accordingly, a need has arisen for providing anti-shock method for head stack assembly, to overcome the above-mentioned drawbacks.